suraj.sun writes: Lawyers working on a $1 billion copyright lawsuit filed by Viacom against Google's YouTube may have uncovered evidence that employees of the video site were among those who uploaded unauthorized content to YouTube.

In addition, internal YouTube e-mails indicate that YouTube managers knew and discussed the existence of unauthorized content on the site with employees but chose not to remove the material, three sources with knowledge of the case told CNET.

The e-mails, according to the sources who asked for anonymity because of the ongoing litigation, surfaced during an exchange of information between the two sides of the legal dispute.

Such evidence could be a major blow to YouTube's defense. If managers possessed "actual knowledge" of copyright infringement on the site and did not quickly remove it, the company may not be entitled to protection under the Digital Millennium Copyright Act's safe-harbor provision, according to legal experts.